Studies show that a fetus’s brain and nervous system require sufficient B12 levels from the mother to develop properly.

Vitamin B12 deficiency in the beginning stages of pregnancy may increase the risk of birth defects, such as neural tube defects. Furthermore, maternal vitamin B12 deficiency may contribute to premature birth or miscarriage (3).

One study found that women with vitamin B12 levels lower than 250 mg/dL were three times more likely to give birth to a child with birth defects, compared to those with adequate levels (4).

For women with a vitamin B12 deficiency and levels below 150 mg/dL the risk was five times higher, compared to women with levels above 400 mg/dL (4).

Summary Appropriate vitamin B12 levels are key to a healthy pregnancy. They’re important for the prevention of brain and spinal cord birth defects.

Maintaining adequate levels of vitamin B12 may help prevent the risk of age-related macular degeneration.

Researchers believe that supplementing with vitamin B12 may lower homocysteine, a type of amino acid that is found in your bloodstream.

Elevated homocysteine levels have been associated with an increased risk of age-related macular degeneration (9, 10).

A study involving 5,000 women aged 40 or older concluded that supplementing with vitamin B12, along with folic acid and vitamin B6, may reduce this risk (11).

The group receiving these supplements for seven years had fewer cases of macular degeneration, compared to the placebo group. The risk of developing any form of the condition was 34% lower, while it was 41% lower for more severe types (11).

Ultimately, further studies are needed to fully understand vitamin B12’s role in promoting vision health and preventing macular degeneration.

Summary Maintaining adequate levels of vitamin B12 decreases homocysteine levels in your blood. This may help prevent the development of age-related macular degeneration.

The effect of vitamin B12 on mood is not yet fully understood. However, this vitamin plays a vital role in synthesizing and metabolizing serotonin, a chemical responsible for regulating mood.

Therefore, vitamin B12 deficiency may lead to decreased serotonin production, which may cause a depressed mood.

Studies support the use of vitamin B12 supplements for improving symptoms of depression in people deficient in this vitamin.

One study in people with depression and low vitamin B12 levels found that those who received both antidepressants and vitamin B12 were more likely to show improved depressive symptoms, compared to those treated with antidepressants alone (12).

Vitamin B12 deficiency has been associated with memory loss, especially in older adults.

The vitamin may play a role in preventing brain atrophy, which is the loss of neurons in the brain and often associated with memory loss or dementia.

One study in people with early-stage dementia showed that a combination of vitamin B12 and omega-3 fatty acid supplements slowed mental decline (15).

Another study found that even vitamin B12 levels on the low side of normal can contribute to poor memory performance. As a result, supplementing with this vitamin may improve memory, even in the absence of a clinically diagnosed deficiency (16).

More research is needed to make sound conclusions on the effect of vitamin B12 supplements on memory and cognitive function.

Summary Vitamin B12 may help prevent brain atrophy and memory loss. More research is needed to conclude if supplementing with this vitamin can improve memory in those without a deficiency.

However, there is currently no scientific evidence to confirm that vitamin B12 supplements are effective in this regard (23).

Therefore, further research is needed to understand the relationship between vitamin B12 and heart health.

Summary Vitamin B12 can decrease blood homocysteine, a type of amino acid that is associated with an increased risk of heart disease. However, research does not currently support the claim that vitamin B12 reduces this risk.

Even though some plant-based milks or grains may have been fortified with vitamin B12, vegan diets are often limited in this vitamin, putting people at risk of deficiency.

If you eat a healthy, varied diet, preventing a vitamin B12 deficiency should be easy. However, if you think that you might be at risk, speak to your doctor.

Vitamin B12 deficiency can most often be prevented or resolved with oral or intramuscular injections.

Summary Risk factors for vitamin B12 deficiency include a decreased ability to absorb this vitamin due to low hydrochloric acid secretion, certain medications or gastrointestinal disease and surgeries. Vegans are also at risk since B12 is only found in animal products.

Vitamin B12 is a water-soluble vitamin that you must obtain through diet or supplements.

It’s responsible for many bodily functions and may benefit your health in various ways, such as by preventing major birth defects, supporting bone health, improving mood and maintaining healthy skin and hair.

Getting enough vitamin B12 through your diet is crucial. However, if you struggle to obtain enough or have a condition that affects absorption, supplements are a simple way to increase your B12 intake.